As a result of many years of professional driving over roads of various constructions and on various terrains, on bridges, or the like adjacent to inland bodies of water and in coastal areas, I have learned that under certain conditions, portions of a driving surface or on a bridge may have ice or frost thereon, and the motorist may suddenly encounter such conditions without prior warning when driving onto a stretch of road that has ice or frost thereon, thereby substantially risking slipping and sliding of the motor vehicle leading to loss of control and/or damage to the motor vehicle and injury to the driver and/or occupants of the passenger car, truck, or bus. At the present time I have no knowledge of any reliable advance warning device for signalling such an icy condition on a motor vehicle driving surface that delineates a particular area of the surface in advance that produces such a problem. A highway, for example, may be constructed in areas subject to snow and/or freezing with a portion of the highway being constructed at a lower elevation than the elevation of the highway approach to such an area and lower than the exit driving area through which the motorist must pass. When driving on road surfaces having differences in elevation in cold weather subject to freezing temperatures, the road surfaces on both sides of the area having the lower elevation may be around freezing temperatures (35 degrees Fahrenheit) but without producing freezing and ice and are therefore not subject to causing slipping and sliding of the motor vehicle, while the area forward of the same road surface having a lower elevation may be a few degrees cooler (32 degrees Fahrenheit) and thereby may be at or below the freezing temperatures, causing ice to be formed in these stretches of the road or the frosting of the surface to produce a hazardous driving condition, especially when no advance warning is provided. When the motorist travels on such a road surface, he may be traveling at a speed that when he unexpectedly enters the icy areas and is surprised as to the driving conditions, the risk of an accident, damage or injury is substantial. This ice condition may also prevail when the driving surface is adjacent a body of water, such as in coastal areas or the like, and the road surface is at different elevations or on a bridge across a body of water or the like. The advance warning signalling of such ice conditions to motorists would substantially reduce the risks of encountering such areas by surprise to thereby minimize accidents, slipping and sliding due to ice or frost conditions on the highway being traveled by the motor vehicle.
At the present time there is in use on highways standard signs with legends that call a motorist's attention to potentially hazardous conditions, such as "Slippery When Wet", "Ice", or the like, but do not segregate any particular stretch of the highway that may be dangerous from those that are usually safe to drive on, i.e., above freezing temperatures. The patent art does disclose various types of devices for sensing air temperature and/or for temperature of a road surface for detecting and warning of icy conditions. All of the known devices are considered to be relatively complex, mechanical and/or electronic devices that are expensive to manufacture and put in use. To my knowledge these patented devices are generally not in use. The known patents include U.S. Pat. No. 2,301,247 of Bronee granted on Nov. 10, 1942. The Bronee patent discloses a rather complex mechanical system for sensing the temperature of the air and the temperature of the surface of a road for indicating an icy formation on a road surface for traffic signalling purposes. Other patents, such as the Clark U.S. Pat. No. 2,849,701, disclose complex electronic systems for sensing a variety of road conditions along a highway and signalling same to a motorist. These types of devices may not only provide a sign with a legend indicating the hazardous conditions, but also the suggested safe driving speed. Devices of this type are designed to return to a normal non-icing condition upon a rise in temperature and the passing of such a condition and are also disclosed in the Lucarelli Pat. No. 2,902,669, the Hulett Pat. No. 3,164,820, Ciemochowski Pat. Nos. 3,596,264 and 3,613,063. Other prior art patents of this type are the Frant Pat. No. 3,229,271 and the Boschung Pat. No. 4,222,044. These patents disclose ice sensing systems that operate at a particular location, such as a bridge, and disclose various types of indicators, none of which are of the simple and inexpensive type and construction of my invention.